Copper Stains and Re-Occuring Iron Stains

[smallpooldad]

I had a Nature 2 for 6 years from 1994 to 2000, then I stopped using it. I have treated for iron with AA treatment about once a year since 2000. The pool registers zero ppm for copper, but is it possible that despite the zero reading the copper stains would remain, in the gunite pool?

Thank you.

 

[Melt In The Sun]

Re: Copper Stains

Yes; copper will only show up on the test if it's dissolved in the water. Since it's already attached to the plaster in the form of a stain, it won't show up on the test.

 

[smallpooldad]

Re: Copper Stains

Melt In The Sun,

Thank you for your reply, that is what I thought but I wanted to make sure my assumption was correct. These copper stains reappear after AA treatment after about 2 weeks, I am now treating the copper stains, one week now, with Jack's Magic "The Copper and Scale Stuff" plus "The Purple Stuff", and today switched to the newer "Magenta Stuff". It seems to be working well, the only issue I have is that it seems to eat a lot of the sequestrant on a daily basis, therefore expensive. I have their sequestrant test kit. The stains however, albeit with a lot of steel brush scrubbing, are nearly gone except for a few shadow spots where they were really heavy. Jack's tech support staff stated that this process removes both copper and iron.

On asking Jack's tech support whether or not the metals stay in solution or are removed they adamantly stated they are chelated out to the filter and will back wash out. This is contrary to what many state on the forum, as I do not yet have an iron test kit I cannot verify either way. But I will report back when I get one, as regards the iron being in solution or not. As stated even though the copper stains are nearly all gone the copper test shows no copper in solution so presumably the copper is chelated out.

Or do I have that wrong, knowing me most likely I am wrong as I am no chemist, and they would not show up if they were in solution?

 

[Melt In The Sun]

Re: Copper Stains

How low can the copper test read? I can't imagine that much copper is contained in a stain; almost certainly too little to reach even .1 ppm in the water if it were dissolved.

How extensive are the stains? You may be able to spot treat them if they're not too extensive. I've read someplace on here that you can put dry acid in a sock for spot treatments...can't find it now.

 

[JasonLion]

Re: Copper Stains

If there are metals in the water they should show up on the test. If the metals are in stains they do not show up in the test. One things to watch out for is that the metal tests aren't perfect. You need to build up a history with a specific test kit to be sure you are using it correctly and getting reliable test results.

Metals sometimes get filtered out, but more often than not they stay in the water. I would love to see how your pool works out, if the metals go away or not.

 

[Durk]

Re: Copper Stains

Good luck! I had a Nature2 cartridge fail and release all its little balls into the pool--then they mostly rolled down the floor into the main drain, ended up in the lint trap and filter, and stained the brand new plaster. I've gotten rid of 80% of the damage with an acid start-up, and I live with the rest (invisible except on windless, cloudy days). Don't forget N2 includes silver as well as copper, just to make things worse. It came free with the pool and I had no idea what I was getting. Grrrrrrrr....

Anyway, please keep us posted.

 

[smallpooldad]

Re: Copper Stains

Thank you all for your replies.

The copper staining was extensive, and after a week it is just barely visible in a few of the places where it was really quite bad.

The Aquarium test kit only starts measuring at 0.25 ppm, then 0.50, etc., so not too sensitive. The test actually produced a completely clear liquid with 10 drops, not a hint of color. Would adding 20 drops show me 0.125 ppm and 40 drops, .0625 ppm, etc?

I will purchase the Taylor Iron K-1716 and Taylor Copper K-1730 test kits, the Iron being my major issue due to airborne delivery into the pool, via our "Trade Winds" which blow up on the mountain where we live at 16 mph to 24 mph on average, year round. I think our municipal supply is OK as there is no staining in toilets, tubs, etc. after 15+ years. Then I will know for sure if the two metals are removed from the pool by Jack's stuff, or merely held in solution.

I will report back in a month or so, as I think the actual removal process will only take another week. Then allow time to see if there is any re-emergence of the stains when the pool is balanced back up from a pH of 6.2 to say pH 7.5, and an alkalinity of 20 ppm to say 60-80 ppm. This might then help others who have this re-emergence of stain issues. If I get the metal test kits in the next week or so by mail, none are available in Honolulu, I will report those readings. I am beginning to believe that these re-emerging stains after the AA treatment were not iron, well at least not much, but the copper stains and possibly scale, the AA treatment just temporarily hiding these underlying issues.

And yes my Nature 2 also came free with the pool. "Beware of ***** bearing gifts".

Question: What are the recommended max ppms for Iron and Copper in a gunite pool?

Finally for interest, today, from my house, I can see sitting about a mile or two off Diamond Head in the ocean, the Anti-Ballistic Missile Radar Dome on its floating oil rig type platform, a really quite impressive site, it must be huge. They bring it to Hawaii I believe for repairs at Pearl Harbor and during the CINCPAC RIMPAC joint exercises which were recently held in our waters.

 

[JasonLion]

Re: Copper Stains

Metal levels of up to 0.3 are usually alright in gunite pools. Fiberglass is much more sensitive, while vinyl is somewhat less sensitive, to metals in the water.

 

[smallpooldad]

Re: Copper Stains

JasonLion,

Thank you and I will let you know as soon as I get the test kits in what the ppms are.

 

[smallpooldad]

Re: Copper Stains

An interesting update but before I start I have still not received the iron test kit. Did test again for copper with 10 drops, the recommended dose, zero copper registered (the first ppm measurement on the color scale is 0.125), then tried 20 drops zero, tried 30 drops zero, finally tied 40 drops zero ppm, so it seems no copper in solution.

I read this post where JasonLion you recommended applying phosphonic acid directly to the spot:

http://www.troublefreepool.com/copper-stains-t7834.html

So although I had just raised the sequestrant from 12 to the 20 ppm recommended for metal removal I added another 20 ppm in total to the spots where I could still view faint stains, 40 ppm in the pool in total. Well I left for the day and returned in the evening before sunset and the pool was quite cloudy. I forgot that adding that much sequestrant would affect the chlorine. This then was going to be a possible algae bloom. I raised the chlorine from FC 1 (possibly lower) to shock levels for a pH of 6.2, Alk of 20, CH 350, and CYA of 25 to 5.5 ppm FC, this equates to a HOCl (as ppm Cl2) of 0.330. I calculated this using the "PoolEquations" spreadsheet, as the shock level at these low readings is much lower than the FC/CYA chart. Then left it overnight with the pump running and the pool was clear in the morning.

But the interesting part was that the faint stains nearly disappeared, they were visible the evening before to even a casual observer. But in the morning if one knew where they were you could still just find them but to someone new to the pool there appears to be no staining at all. These observations were made in the shade in the early morning, in the sun no stains are visible. There are stains but they are very, very faint. Somehow the combination of high sequestrant "The Magenta Stuff" and FC at shock levels seems to have helped. The Sequestrant had moved down to 14 ppm in the morning, I raised it to 20 ppm, and the FC was 4.5. I will let the FC settle to between be 2.5 and 3.0, a HOCl (as ppm Cl2) of between 0.137 and 0.167.

Well progress is being made, it seems a higher concentration of FC and adding more than the recommended dosage of sequestrant is more effective at removing the stains. Why I do not know, can anyone explain? This albeit more expensively as one has to add more sequestrant and more FC to offset the effect, still cheaper than re-plastering.

I did read that tannin stains have iron in them and are much harder to remove than no-tannin iron stains. I definitely had tannin stains as years ago we had a large tree near the pool. And at that time 1994 to 2000 I knew nothing about sequestrants, etc.

I also read in that same post above that if one does have copper stains, Ascorbic acid will actually make them worse. How many times did I treat with AA I dread to think, maybe 10 plus.

Supposed to get the iron test kit tomorrow, our local pool store found one on the Big Island of Hawaii. Hopefully the chemicals will not be out of date and I can report back as to whether or not there is iron, in solution.

 

[bk406]

Re: Copper Stains

My experience with the Taylor iron kit is that it will only measure iron thats dissolved in the water. Iron thats oxidized or precipitated out, will not show up. Iron thats sequestered wont show up either. I know I have a bit of iron in my pool, but when I use the Taylor kit, it doesnt show up. I have sequesterant in the pool, so thats why it doesnt show up on the test. Even when I can see some light green in the water, it wont register. Im not sure how the taylor test works, but it sems to measure only reduced, dissolved iron.

 

[smallpooldad]

Re: Copper Stains

bk406,

Well that is not good. My water shows no light green tinge. When you write "Even when I can see some light green in the water", do you mean particles or is the water light green? Are you using the Taylor Iron K-1716 kit which measures 0-2.0 ppm or one the less sensitive 1-10 ppm kits?

Does anyone know of a test kit that will show iron in the water? Or is it possible to raise the sample water pH so that it precipitates out of the sequestrant, and/or neutralize the sequestrant, so one could identify the amount in ppms? And/or would adding chlorine help the test sample to neutralize the sequestrant, and if so how much?

Thank you for this information.

 

[chem geek]

Re: Copper Stains

My experience with the Taylor iron kit is that it will only measure iron thats dissolved in the water. Iron thats oxidized or precipitated out, will not show up. Iron thats sequestered wont show up either. I know I have a bit of iron in my pool, but when I use the Taylor kit, it doesnt show up. I have sequesterant in the pool, so thats why it doesnt show up on the test. Even when I can see some light green in the water, it wont register. Im not sure how the taylor test works, but it sems to measure only reduced, dissolved iron.

Earlier this year when I asked Taylor about whether copper that was sequestered would get measured in the test, they said that there is no mention or note that sequestering agents will affect the result of the test. Because the metal is not physically removed from the water, the thiocarbamate method determines the total amount of copper in the water. I would presume that the same is true of the iron test.

When the water is colored, that doesn't necessarily mean it has metal ions in it. It's more likely to be iron or copper combined with carbonates, hydroxide-oxides or in some cases cyanurates. That is, it is precipitate solids that are fine enough to be dispersed in the water. Of course, if the pH were reasonably low, one would expect any such precipitates to be in equilibrium with metal ions in the water that should measure in the tests.

So we have an inconsistency here between what is supposed to be measured in the tests vs. what you have seen.

 

[bk406]

Re: Copper Stains

So we have an inconsistency here between what is supposed to be measured in the tests vs. what you have seen.

It would seem so. As i said, I know there is some level of iron in my pool. It could be the amount is below the level of detection. That would mean, however, that you can see the color show up at iron levels below 0.2 ppm (I assume thats the limit of detection since thats the lowest standard on the block). I dont understand it either. I think Dave has ron in his water as well, but cant get it to show up with the Taylor test either. Is that right Dave?

 

[duraleigh]

Re: Copper Stains

I spoke with Taylor 3 days ago about a very perplexing problem I had this Spring wherein the only logical conclusion was iron in the water. However, the Taylor 1716 could not detect it.

Taylor's answer was that that test should be capable of detection regardless of the form.

 

[bk406]

Re: Copper Stains

Well, there's a disconnect someplace that I dont understand. The green tinge I see in my pool only happens when I do the following:

1) add water that has up to 1.5 ppm dissovled iron
2) wipe down with ascorbic acid the skimmer plate and inside of skimmer, return/suction fittings, and light housing to remove iron stains. As soon as I do that, I see green tinged water. Slight, but its there.
3) Dont add sequesterant for 2-3 weeks and have a high swimmer load.

When it happens, I test with the Taylor kit and get no iron reading. But, I can add a phosphonic acid based sequesterant, and I clears up in 2-3 hours.

 

[chem geek]

Re: Copper Stains

You should contact Taylor and tell them what you are experiencing. This is unacceptable to have a test that is apparently not working. It's not a cheap test and we really need something reliable for metal testing.

 

[smallpooldad]

Re: Copper Stains

Spoke with Taylor Technologies Tech Support, they stated that the sequestrant will not interfere with the iron test, excessive iron over 2.0 would interfere with the test, and also could show no iron. They further stated that Jack's Magic "The Magenta Stuff" will both sequester and chelate out the iron and copper to the filter (Jack's Magic stated the same), and therefore no iron should register in the test, especially if it is under 0.2.

As mentioned there are still a few very faint stains in a few areas, spoke with Jack's Tech Support, they stated that these few areas, mainly the steps, should feel rougher and the areas that have no stains should feel quite smooth, they do feel rougher. This indicates scale, so the treatment cannot get at it, and I should keep brushing, but the area is so rough I think I need to acid wash them. I told them I plan to drain the pool and acid wash the steps and a couple of other small areas. After refilling, the tech suggested, before adding either chlorine or salt but balancing pH and hardness, I should put 5 lbs of O2 Non-chlorine Shock in the pool and let it work for about half an hour, and this will help get the pool even cleaner. Then add chlorine, then the salt. So hopefully I will have solved the mystery of the re-occuring after AA treatment stains.

Does adding 5 lbs Jack's O2 Non-Chlorine Shock sound ok? And when I add chlorine will I need to add more, and if so how much more?

The pool is looking very, very good.

Hope this helps.

 

[bk406]

Re: Copper Stains

They further stated that Jack's Magic "The Magenta Stuff" will both sequester and chelate out the iron and copper to the filter (Jack's Magic stated the same), and therefore no iron should register in the test, especially if it is under 0.2.

.

Well, this is contrary to anything I've heard or read. I'm not saying it's wrong, it's just not anything i've heard of. If it's true, then that could explain why after i add sequesterant i dont read any iron. Still doesnt explain why i dont read any iron right after i add water but get a green pool. I'm assuming any phosphonic acid based sequesterant would chelate to the filter, not just Jack's. I'm still not convinced a sequesterant will chelate it out to where it's filterable.

 

[smallpooldad]

Update:

Got the Taylor test kit for iron and as I thought, the fill water thankfully contains no measurable iron; measured the pool water and that to has no measurable iron. Unlike you bk406 my water is not colored.

I am religious about daily checking the sequestrant level to make sure it is high enough to do the in-pool acid wash, although the tech at Jack's said once a week is enough, but with my scale and copper stains I thought otherwise. I go through about 8 ozs of "The Magenta Stuff" a day to maintain a level of 20 ppm, so presumably it is soaking up a lot of something. If I did not have Jack's sequestrant test kit my guess would be that I to may have some coloration as well, my levels of sequestrant might be too low. This of course is just a guess. bk406, are you using the sequestrant test kit?

I have been brushing the steps with a steel brush as often as I can. Brushed them about 30 times last night and again very early this morning and they are definitely improving, hopefully I will not have to acid wash.